Technetium-99m radiopharmaceutical preparation problems: 12 years of experience

Chemical reactions involved in preparing 99mTc radiopharmaceuticals occasionally result in products of substandard purity. A retrospective examination of preparation problems that occurred in the author's institution was conducted to better define the incidence, recognize patterns and identify causes of substandard 99mTc radiopharmaceutical products.

All 99mTc radiopharmaceutical preparation and quality control testing records for the years 1986-1997 were reviewed, and preparation factors associated with substandard products were identified and examined.

Fifty of 20,972 (0.2%) 99mTc products had substandard radiochemical purity; none were administered to patients. Twenty-eight of the 50 substandard products (56%) involved macroaggregated albumin with the remainder divided among in vitro red blood cells, exametazime, disofenin, sestamibi, mertiatide and sulfur colloid. Thirty-three of the 50 (66%) involved 99mTc-pertechnetate obtained as the first elution of a new generator and/or 99mTc-pertechnetate more than 12 hr old. Several of the substandard products involved other preparation factors and/or human error.

The majority of substandard 99mTc radiopharmaceutical products involved the use of 99mTc-pertechnetate containing excessive amounts of 99Tc and/or oxidizing impurities to prepare products containing relatively small amounts of stannous. Although substandard products are an infrequent occurrence, radiochemical purity testing should be performed routinely on all 99mTc radiopharmaceuticals before patient administration.